fetchGit and flake: add commit signature verification tests

This adds simple tests of the commit signature verification mechanism of
fetchGit and its flake input wrapper.
OpenSSH is added to the build dependencies since it's needed to create
a key when testing the functionality. It is neither a built- nor a
runtime dependency.

flake.nix

@@ -183,6 +183,7 @@
             buildPackages.git
             buildPackages.mercurial # FIXME: remove? only needed for tests
             buildPackages.jq # Also for custom mdBook preprocessor.
+            buildPackages.openssh # only needed for tests (ssh-keygen)
           ]
           ++ lib.optionals stdenv.hostPlatform.isLinux [(buildPackages.util-linuxMinimal or buildPackages.utillinuxMinimal)];
 

tests/functional/fetchGitVerification.sh

@@ -0,0 +1,76 @@
+source common.sh
+
+requireGit
+[[ $(type -p ssh-keygen) ]] || skipTest "ssh-keygen not installed" # require ssh-keygen
+
+enableFeatures "source-signature-verification"
+
+clearStore
+
+repo="$TEST_ROOT/git"
+
+# generate signing keys
+keysDir=$TEST_ROOT/.ssh
+mkdir -p "$keysDir"
+ssh-keygen -f "$keysDir/testkey1" -t ed25519 -P "" -C "test key 1"
+key1File="$keysDir/testkey1.pub"
+publicKey1=$(awk '{print $2}' "$key1File")
+ssh-keygen -f "$keysDir/testkey2" -t rsa -P "" -C "test key 2"
+key2File="$keysDir/testkey2.pub"
+publicKey2=$(awk '{print $2}' "$key2File")
+
+git init $repo
+git -C $repo config user.email "foobar@example.com"
+git -C $repo config user.name "Foobar"
+git -C $repo config gpg.format ssh
+
+echo 'hello' > $repo/text
+git -C $repo add text
+git -C $repo -c "user.signingkey=$key1File" commit -S -m 'initial commit'
+
+out=$(nix eval --impure --raw --expr "builtins.fetchGit { url = \"file://$repo\"; keytype = \"ssh-rsa\"; publicKey = \"$publicKey2\"; }" 2>&1) || status=$?
+[[ $status == 1 ]]
+[[ $out =~ 'No principal matched.' ]]
+[[ $(nix eval --impure --raw --expr "builtins.readFile (builtins.fetchGit { url = \"file://$repo\"; publicKey = \"$publicKey1\"; } + \"/text\")") = 'hello' ]]
+
+echo 'hello world' > $repo/text
+git -C $repo add text
+git -C $repo -c "user.signingkey=$key2File" commit -S -m 'second commit'
+
+[[ $(nix eval --impure --raw --expr "builtins.readFile (builtins.fetchGit { url = \"file://$repo\"; publicKeys = [{key = \"$publicKey1\";} {type = \"ssh-rsa\"; key = \"$publicKey2\";}]; } + \"/text\")") = 'hello world' ]]
+
+# Flake input test
+flakeDir="$TEST_ROOT/flake"
+mkdir -p "$flakeDir"
+cat > "$flakeDir/flake.nix" <<EOF
+{
+  inputs.test = {
+    type = "git";
+    url = "file://$repo";
+    flake = false;
+    publicKeys = [
+      { type = "ssh-rsa"; key = "$publicKey2"; }
+    ];
+  };
+
+  outputs = { test, ... }: { test = test.outPath; };
+}
+EOF
+nix build --out-link "$flakeDir/result" "$flakeDir#test"
+[[ $(cat "$flakeDir/result/text") = 'hello world' ]]
+
+cat > "$flakeDir/flake.nix" <<EOF
+{
+  inputs.test = {
+    type = "git";
+    url = "file://$repo";
+    flake = false;
+    publicKey= "$publicKey1";
+  };
+
+  outputs = { test, ... }: { test = test.outPath; };
+}
+EOF
+out=$(nix build "$flakeDir#test" 2>&1) || status=$?
+[[ $status == 1 ]]
+[[ $out =~ 'No principal matched.' ]]

tests/functional/local.mk

@@ -55,6 +55,7 @@ nix_tests = \
   secure-drv-outputs.sh \
   restricted.sh \
   fetchGitSubmodules.sh \
+  fetchGitVerification.sh \
   flakes/search-root.sh \
   readfile-context.sh \
   nix-channel.sh \